Pneumatic tires require repair or replacement from time to time because of sustained wear or damage. To effectuate such repair or replacement, it is generally required that the defective tire be removed from its associated wheel rim and a new or repaired tire may be mounted to the rim.
A variety of tools of varying configurations have been developed for providing a user with mechanical advantage in mounting or demounting a tire to a wheel rim. Such tools typically comprise an elongate bar having a handle at one end and an opposite working end adapted for insertion between the bead of a tire and its associated wheel rim. The working end of the tool frequently has a flattened or tapered portion to facilitate insertion of the working end between the tire bead and the wheel rim. The working ends of known tools are configured, in profile, as either straight, curved, or angled.
To utilize the demounting implement, the tool working portion is inserted manually by the user between the bead of the tire and its associate wheel rim. Thereafter, the user applies pressure on the handle, making a lever of the tool and utilizing the wheel rim as a fulcrum. Pressure upon the handle causes the tool to engage the tire bead and move a segment of the bead over the rim, thereby disengaging the bead segment from the rim. The tool is then redeployed along the tire to an adjacent location and the procedure is repeated upon a corresponding adjacent bead segment. Repeated redeployment and utilization of the tool about the periphery of the tire pulls a sufficient length of the tire bead over the rim until the tire is free for removal from the rim in its entirety. In more recent years, machines have been developed which rotate the tire in conjunction with the use of the tool to alleviate the need for moving the tool. However, mounting and demounting a tire to a commercial truck wheel is often performed manually.
Use of the wheel rim as a fulcrum about which to lever a tire tool provides an opportunity for the tool, typically made of iron or steel, to damage the finish of the wheel. Whether a wheel's surface is painted steel, finished aluminum, or other chrome-like surface, the result of repeated tool contact with the wheel is scratches, dents and abrasions to the wheel rim. A typical commercial truck wheel is expensive, and when one considers all of the wheels on an 18-wheeler semi-truck, the cost can get extremely expensive. Considering that commercial trucks may cover 100,000 miles or more per year, tires must be changed at least several times per year, with each change presenting an opportunity to damage the wheel. Damage to wheels, apart from being cosmetically undesirable, can have functional effects on the serviceability of both the wheel and the tire. Dents and abrasions to the wheel rim can be detrimental to the balance of a wheel, thereby causing the wheel to vibrate and possibly damaging the vehicle suspension or causing loss of vehicle control. The wheel rim is also the site where an airtight seal with the tire bead is and must be formed. Damage or abrasion to the wheel rim can prevent the formation of such an airtight seal with the tire bead. Worse still, if the wheel rim is sufficiently damaged or abraded; it can actually cut or puncture the tire bead, thereby rendering the tire dangerous and useless.
Certain known tire changing tools not only use the wheel rim as a fulcrum, but also contact the well of the wheel. Typically the well is painted or finished with a weather-resistant coating, intended to protect the underlying metal wheel from oxidation. Contact with a steel tire tool can abrade or scratch the finish, thereby exposing the metal to corrosion. Although not as immediately damaging to a wheel as physical bending or abrading of the rim, such resultant oxidative corrosion, if left unchecked, will lead to eventual rust-through of the wheel, rendering it useless and worthless.
Similar concerns exist for passenger automobile wheels. Traditionally, automobile wheels were fairly inexpensive, as they were made of steel. The use of hard metal implements for the mounting and demounting of tires was necessary yet caused little concern relative to damaging the steel wheels.
With the increasing use of light alloys, automobile wheels are now more susceptible to damage from hard metal implements used during the mounting and demounting of tires. The driving force behind the use of light alloy wheels in modern cars is the desire to improve traction and handling. Assuming that a car chassis is not modified, the rolling diameter of any tire/wheel combination installed on a car must remain constant. Wider and lower profile tires allow an increase in the size of the contact patch while maintaining a rolling diameter substantially the same as the manufacturer intended. A larger contact patch affords improved handling properties to the automobile. Such lower profile tires often have an increased speed rating relative to original equipment manufacturer's tires, and are often are available as aftermarket upgrades. In order to maintain a constant rolling diameter while improving handling properties, a tire having a lower profile must accompany a wheel having a correspondingly larger diameter.
Not long ago, 13- or 14-inch wheels wrapped in 65 or 75 series tires were the norm. Today, very few, if any, passenger cars are equipped with less than 15-inch wheels. Many cars now have tires with low profile sidewalls and diameters upwards of 25″ standard, with 16-, 17- or even 18-inch diameter wheels standard. Wheel sizes up to 22-inches are available as aftermarket upgrades. As previously stated, these larger diameter tires having wider contact patches require larger diameter wheels to maintain a constant rolling diameter. Hence, aspect ratios of 55, 45, 35 and even 25 are now available. Light alloy wheels and the accompanying low profile, speed rated tires can get very expensive.
In light of the expense of wheels and tires for both commercial and passenger vehicles and their susceptibility to damage during mounting and demounting, the motivation to protect both tires and wheels during mounting and demounting on today's cars is readily apparent.
In the past, mechanics, both professionals and do-it-yourselfers, have developed home made solutions to the problem of wheel damage during tire mounting and demounting. A variety of imperfect solutions have been tried. Some have used heavy tape, such as duct tape or electrical tape to protect the rim of expensive alloy wheels from scratches incurred during tire mounting and demounting. Others have cut plastic beverage bottles into strips and wedged the strips into the gap between the wheel rim and tire bead to protect the wheel from damage. One more sophisticated attempt at protecting the wheel rim includes a hard plastic clip that slides over the rim edge and is provided with a rope to secure the clip in place. As a shop solution, many mechanics merely use a rag, another piece of cloth, or even a work glove. However, none of these items are specifically designed for the task at hand. None of these items are durable beyond a few uses. Moreover, these items are not readily fastened to the wheel rim in a secure manner that would allow the operator to devote his full attention to applying the careful attention and proper force required to mount or demount a tire to/from a wheel.